/div>Continent, Western Hemisphere. The world's fourth largest continent, it is bounded by the Caribbean Sea to the northwest, the Atlantic Ocean to the northeast, east, and southeast, and the Pacific Ocean to the west. It is separated from Antarctica by the Drake Passage
and is joined to North America by the Isthmus of Panama. Area: 6,882,027 sq mi (17,824,370 sq km). Pop., 2008 est.: 378,448,500. Four main ethnic groups have populated South America: Indians, who were the continent's pre-Columbian inhabitants; Spanish and Portuguese who dominated the continent from the 16th to the early 19th century; Africans imported as slaves; and the postindependence immigrants from overseas, mostly Germans and southern Europeans but also Lebanese, South Asians, and Japanese. Nine-tenths of the people are Christian, the vast majority of whom are Roman Catholic. Spanish is the official language everywhere except in Brazil (Portuguese), French Guiana (French), Guyana (English), and Suriname (Dutch); some Indian languages are spoken. South America has three major geographic regions. In the west, the Andes Mountains
, which are prone to seismic activity, extend the length of the continent; Mount Aconcagua
, at 22,831 ft (6,959 m), is the highest peak in the Western Hemisphere. Highlands lie in the north and east, bordered by lowland sedimentary basins that include the Amazon River
, the world's largest drainage basin, and the Pampas
of eastern Argentina, whose fertile soils constitute one of South America's most productive agricultural areas. Other important drainage systems include those of the Orinoco
and São Francisco
rivers and the Paraná
–Río de la Plata system. Four-fifths of South America lies within the tropics, but it also has temperate, arid, and cold climatic regions. Less than one-tenth of its land is arable, producing mainly corn (maize), wheat, and rice, and about one-fourth is under permanent pasture. About half is covered by forest, mainly the enormous but steadily diminishing rainforest of the Amazon basin. Almost one-fourth of all the world's known animal species live in the continent's rainforests, plateaus, rivers, and swamps. South America has one-eighth of the world's total deposits of iron and one-fourth of its copper reserves. Exploitation of these and numerous other mineral resources are important to the economies of many regions. Commercial crops include bananas, citrus fruits, sugar, and coffee; fishing is important along the Pacific coast. Trade in illegal narcotics (mostly for export) is a major source of revenue in some countries. Most countries have free-market or mixed (state and private enterprise) economies. Income tends to be unevenly distributed between large numbers of poor people and a small number of wealthy families, with the middle classes, though growing, still a minority in most countries. Asiatic hunters and gatherers are thought to have been the first settlers, probably arriving less than 12,000 years ago. The growth of agriculture from c.
2500 BCE (it had begun some 6,000 years earlier) initiated a period of rapid cultural evolution whose greatest development occurred in the central Andes region and culminated with the Inca
empire. European exploration began when Christopher Columbus
landed in 1498; thereafter Spanish and Portuguese adventurers (see conquistador
es) opened it for plunder and, later, settlement. According to terms of the Treaty of Tordesillas
, Portugal received the eastern part of the continent, while Spain received the rest. The Indian peoples were decimated by this contact, and most of those who survived were reduced to a form of serfdom. The continent was free of European rule by the early 1800s except for the Guianas
. Most of the countries adopted a republican form of government; however, social and economic inequalities or border disputes led to periodic revolutions in many of them, and by the early 20th century most had fallen under some form of autocratic rule. All joined the United Nations after World War II (1938–45), and all joined the Organization of American States
in 1948. By the second half of the 20th century most countries had begun to integrate their economies into world markets, and by the 1990s most had embraced democratic rule.